I cannot commit when such functionality will be ready. Meanwhile you can hook for the RadTreeListView.AddingNewDataItem event cancel edit and insert item within the underlying collection (if it supports INotifyCollectionChanged this item will be added within RadTreeListView). After that you can find this new item and put it in edit mode.
I'm attaching a sample application that demonstrates this approach.
P.S. The example works correctly only when first level item (employee) is selected, but you should get the idea.
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